When manufacturing a thermoplastic resin molded product, a pellet that is made of resin raw material (hereinafter, simply referred to as “pellet”) is used in some cases. As one method of molding the pellet, a strand-cut method has been known (PTL 1).
FIG. 10 is a diagram for explaining a strand-cut method disclosed in PTL 1. As illustrated in FIG. 10, in the strand-cut method, the resin raw material is melted, and the melted resin raw material is extruded from a die 2 by an extruder 1. A through hole is formed in the die 2. The resin raw material is extruded from the through hole and formed in a string shape, and thus a strand 3 is manufactured. Then, a pellet 5 is completed by cutting the strand 3 in a predetermined length using a cutting device 4.
In recent years, a technique for manufacturing the strand by using a die that includes a plurality of through holes has been proposed (PTL 2). The plurality of through holes are arranged in a direction orthogonal to the direction in which the resin raw material is extruded (hereinafter, the direction is referred to as a “width direction”). The die is attached to the extruder via a flow passage member (also called as a “die supporting device”).
FIG. 11 is a schematic diagram of the flow passage member and the die disclosed in PTL 2. As illustrated in FIG. 11, the flow passage member 6 defines a flow passage 9 that allows the through holes 8 of the die 7 to communicate with an outlet (not illustrated) of the extruder. The width of an inflow port 10 of the flow passage 9 (referred to as a dimension of the width direction) is smaller than the width of an outflow port 11 of the flow passage 9, and the flow passage 9 gradually spreads in the width direction toward the outflow port 11 from the inflow port 10.
Since the flow passage 9 has such a shape, a first path R1 that reaches to the through holes 8 without proceeding in the width direction from the inflow port 10 and a second path R2 of the resin raw material that reaches to the through holes 8 while proceeding in the width direction from the inflow port 10 are formed in the flow passage 9. Therefore, the resin raw material that flows into the flow passage 9 from the extruder is guided into the plurality of through holes 8, and thus it is possible to manufacture collectively a plurality of strands. As a result, it is possible to manufacture more pellets in a shorter time.